1. Field of Invention
This invention relates to devices used for sanitizing air conditioning and heating system ducts, specifically to a compact user-friendly, portable air duct sanitizing apparatus and method, for new construction as well as retrofitting to existing air conditioning and heating systems in commercial and residential buildings, which can be either professionally or owner installed, with routine maintenance thereafter being easily and safely performed by the owner or other non-professional. The sanitizing apparatus of the present invention comprises a system control unit with a housing that supports a refillable non-pressurized reservoir of liquid sanitizing agent, which is removably attached to the housing without opening the housing cover. In addition the housing supports and protects a 24-volt electric pump capable of moving fluid through tubing at a pressure of approximately 60 psi and a fully automated 24-volt programmable timer with power loss backup. The sanitizing apparatus also comprises a plurality of misting nozzles each capable of creating a fine mist having droplets with a maximum diameter dimension of approximately 250xcexc. Each misting nozzle is connected via tubing between the pump and one of the air ducts targeted for sanitizing, with at least one misting nozzle being inserted into each of the air ducts, as well as into the main plenum to which the air ducts are connected. When more than one air duct is targeted for sanitizing, the misting nozzles are connected to a branching array of fluid carrying tubing rated to withstand a maximum pressure of approximately 200 psi that has a trunk line connected to a single hose fitting on the pump. The pump in each system control unit housing is selected to provide liquid sanitizing agent to a maximum of approximately six air ducts. In addition, the present invention also comprises electrical connection means between the 24-volt programmable timer and the air handler of the air conditioning or heating system with which it is associated that allows the sanitizing apparatus to be internally powered through the associated air conditioning or heating system. The system control unit housing of the present invention is preferably mounted in commercial or residential structures in a location remote from the air conditioning ducts, where it can be easily accessed for timer reprogramming and fluid reservoir exchange or refill. The fine mist entering the air ducts is evenly dispersed therein by the fan of the associated air conditioning or heating system, to coat the inside of the air ducts so as to kill bacteria, viruses, fungi, yeast, algae, molds, and mildew over a period of time and thereafter maintain the air ducts in a sanitized condition. As a result, the air duct sanitizing apparatus of the present invention also comprises a fan relay to by-pass the air conditioning or heating system thermostat during such time when the fan is not in an operating mode and it is needed to assist in mist dispersal. Optional use of a planar polyvinyl chloride (PVC) mounting board for electrical components that is removable from the housing not only facilitates manufacture by making it easier for the people assembling the present invention to connect the wiring between electrical components, it also facilitates servicing and replacement of electrical components since the mounting board is easily releasable from the installed housing, typically by unfastening the nuts respectively attached to two bolts. Safety features of the present invention include the high-pressure rated tubing, the reduced voltage timer and pump, a pump that safely operates wet or dry should the operator fail to anticipate timely replacement or refill of the reservoir before all of the fluid therein is completely used, the pump also having a fluid loop should the fluid discharge opening of the pump become inadvertently blocked, and the non-pressurized supply of low toxicity non-flammable sanitizing agent. Although not limited thereto, chlorine dioxide is the sanitizing agent preferred for use with the present invention, as it has a low toxicity and a category III EPA safety rating. In addition to air duct sanitizing, the present invention can also be used for air purification and aromatherapy.
2. Description of Prior Art
The interior walls of the air ducts of ventilation systems are subject over time to the accumulation of particulate matter, as well as the growth of algae, yeast, fungi, bacteria, molds, and mildew. Also, the air drawn through such ducts may contain bacteria and viruses that are so small in size they cannot be removed by filtration. As a result, the continued recycling of air with no conditioning other than filtration can lead to high levels of allergens and other contaminants in ventilation system ducts that can cause those sensitive to them to experience discomfort and/or become ill. Systems to sanitize and condition air in ventilation systems are known. However, most are expensive and/or require professional installation, maintenance, or both. The present invention comprises an air duct sanitizing, de-odorizing, conditioning, and purification system that is user-friendly and has a compactly configured lightweight system control unit housing that can be installed by a non-professional in any location convenient for easy maintenance access. The present invention also has built-in safety features that allow essentially risk-free routine owner maintenance and use. Further, through simple exchange of the non-pressurized fluid reservoir for one containing a different chemical solution, and easy adjustments made to the programmable timer, alternative uses of the present invention can include aromatherapy and air purification.
The invention thought to be the closest in concept to the present invention is the invention disclosed in U.S. Pat. No. 5,281,401 to Bryson, Sr. (1994). However, many important differences exist between the Bryson, Sr. invention and the present invention. The Bryson, Sr. invention comprises a container with a one-way valve for permitting the inflow of air into the container, a pressurized cartridge positioned within the container and adapted for dispensing a vapor into the container, an intermittently operable air and vapor pump, a timer for intermittent activation of the pump with the periods of operation and non-operation being independently variable, and conduit for conveying the air and vapor mixture between the container and the pump, as well as between the pump and an air duct. When multiple segments of conduit are joined, the Bryson, Sr. invention contemplates the use of a valve to adjust the vapor flow into various portions of the conduit. Also, in the Bryson, Sr. invention two independent timers are preferred, one to control the operation time and the other to control the non-operation time. The control box for the Bryson, Sr. invention may be attached directly to the outside surface of an air duct, or in the alternative situated remotely from the duct into which the Bryson, Sr. invention directs its air and vapor mixture. Also, a power supply cord in the Bryson, Sr. invention electrically connects the pump and timer to a standard electrical outlet. As the liquid in the cartridge is spent, the amount of vapor in the canister after a period of rest will become reduced. As a result, timer adjustment is required in the Bryson, Sr. invention when the cartridge fluid level is reduced to allow for more uniform distribution of the vapor. In contrast, the present invention comprises a fully automated 24-volt programmable timer with power loss backup, a non-pressurized reservoir of liquid sanitizing agent which can be refilled or replaced by a new reservoir having the same or different liquid sanitizing or aromatherapy agent, a plurality of nozzles each capable of creating a mist of droplets having a maximum diameter dimension of approximately 250xcexc with at least one of the nozzles being inserted into each of the air ducts targeted for sanitizing and at least one nozzle being inserted into the main plenum to which the air ducts are connected, each nozzle being attached on the distal end of a segment of fluid carrying tubing rated at approximately 200 psi that is connected between the pump and the air duct or main plenum, and electrical connection means between the 24-volt programmable timer and the air handler of the air conditioning or heating system that allows the sanitizing apparatus to be internally powered thereby at reduced voltage without the limitation of having to position the system control unit housing near to an electrical outlet or the further expense of a step-down transformer to convert municipally provided higher voltage electricity to the lower 24-volt alternating current required for safe non-professional operator use. The pump of the present invention is optimally used with no more than a maximum of approximately six misting nozzles for uniform and effective mist coating of air duct interior surfaces. The present invention has no mixing chamber for air and vapor similar to the Bryson, Sr. invention, and no one-way valve to draw air into a vapor-filled chamber which when subjected to vacuum pressure creates an air and vapor mixture that is then circulated by a pump through conduit for dispensing into the atmosphere of an air duct. Instead, the present invention pump is used to draw sanitizing liquid through various branching segments of tubing each ending in a misting nozzle. The mist is only created as the liquid is forced through the nozzles. Thus, since there is no vapor in the fluid reservoir and it is not a mixing chamber, no timer adjustment is required to maintain a threshold level of vapor in the fluid reservoir for mixing and distribution as the sanitizing agent is consumed. Further, a fan relay is used to by-pass the thermostat of the air conditioning or heating system with which the present invention is associated to activate its fan when the fan is not already in an operational mode so that the fan can run concurrently with the pump and be used to disperse the 250xcexc or smaller mist droplets evenly throughout the air ducts. In addition to the fan relay, the present invention also comprises a full bridge rectifier that is not disclosed in the Bryson, Sr. invention. The pump of the present invention is also adapted to operate safely wet or dry should the owner forget to exchange or refill the removable reservoir before all of the sanitizing fluid therein is completely used. Also, for operator safety and to avoid pump failure, the pump has a fluid by-pass loop in the event that its discharge opening becomes inoperable for any reason, and the electrical components may optionally be attached to a planar mounting board releasable from the system control unit housing for ease in manufacture as well as servicing convenience. No air duct sanitizing systems are known that have all of the advantages offered by the present invention.
The primary object of this invention is to provide an air duct sanitizing system that safely and thoroughly kills bacteria, viruses, algae, fungi, yeast, mold, and mildew with continued use in both residential and commercial buildings. It is a further object of this invention to provide an air duct sanitizing system that is lightweight and compact in configuration with components selected for safe and easy installation, operation, and maintenance by professionals as well as non-professionals. It is also an object of this invention to provide an air duct sanitizing system that is user-friendly and reliable, requiring minimal operator maintenance or attention after initial installation. A further object of this invention is to provide an air duct sanitizing system that is effectively used in new construction, and can also be easily retrofitted to the air ducts in existing air conditioning and heating systems. It is also an object of this invention to provide an air duct sanitizing system with a system control unit that has only reduced voltage electrical connections to enhance the safety of non-professional operators. It is also an object of this invention to provide an air duct sanitizing system that can be quickly converted for aromatherapy applications, as well as air purification applications wherein the chemicals used require temporary building evacuation and a cure period.
As described herein, properly manufactured and used, the present invention would provide an air duct sanitizing system and method for the safe and thorough killing of bacteria, viruses, algae, fungi, yeasts, mold, and mildew with continued use, and could alternatively be put to aromatherapy or air purification use. Liquids approved by the U.S. Environmental Protection Agency for air duct sanitizing purposes, such as but not limited to low toxicity non-flammable chlorine dioxide, would be periodically dispensed by the present invention into the air ducts of populated buildings and dispersed by the fan of the air conditioning or heating system with which the present invention is associated so that the mist droplets of chlorine dioxide evenly coat the interior surfaces of the air ducts targeted for sanitization. Once the present invention was installed either professionally or by the owner, the professional operator, building owner, or other non-professional maintenance personnel could easily maintain its function by periodically refilling the fluid reservoir or simply exchanging an empty reservoir for a new one. Due to its low category III safety rating, when chlorine dioxide is used as the sanitizing agent for the present invention, discarded fluid reservoirs would not require any special handling or disposal. In the alternative, when air purification is required, it could be accomplished by simple exchange of the removable fluid reservoir for one providing the appropriate air purification chemical, temporary evacuation of occupants from the building, and continued circulation of the air purification mist through the air ducts and building for a predetermined period of time, followed by a cure period sufficient to allow dissipation of chemicals to the safe level required for renewed human occupancy. The same quick conversion of the present invention into an aromatherapy system can be achieved by simple exchange of a fluid reservoir filled with sanitizing agent and replacement with a fluid reservoir providing the appropriate non-pressurized aromatherapy liquid, as well as easily performed timer adjustment, if required. In the alternative, pleasing scents can be added to the air duct sanitizing agent to achieve aromatherapy objectives. While the present invention is suitable for new construction, it can also be easily retrofitted to existing air conditioning and heating systems since it comprises a compact pre-assembled system control unit and an easily constructed branching array of fluid carrying tubing that contains a misting nozzle within each of its distal ends so that a mist having droplets with a maximum diameter dimension of approximately 250xcexc is directly injected into the main plenum, as well as into each individual air duct connected to the main plenum. The nozzle-duct connections are purposefully made close to the main plenum to best achieve a thorough coating of mist on all interior surfaces of each air duct. The tubing can be made into a variety of suitable branching configurations through the use of T-shaped hose connectors. Electrical outlet access is not a concern in positioning the sanitizing system control unit housing, since a direct electrical connection is made between the air handler of the associated air conditioning system and the sanitizing system control components that allows the present invention to be internally powered through the associated air conditioning or heating system. Such internal power connection also reduces the cost of the system control unit as it eliminates the need for a step-down transformer to provide the 24-volt reduced level of power desired within the system control unit for operator safety. Should a building have multiple air conditioning or heating zones to manage airflow, it is contemplated for one of the present invention air duct sanitizing systems to be used in association with each zone. The system control unit housings used in each zone could then be consolidated in one location for efficient maintenance, or in the alternative they could be located independently from one another, as dictated by available space or as otherwise desired. The sanitizing system control unit housings are lightweight and compact, and therefore easily mounted to most surfaces. Also, since they are made from plastic, such as polypropylene, they are virtually maintenance-free and resistant to the corrosive nature of some of the chemicals used to sanitize air ducts. Connection of the misting nozzles to the air ducts can be easily accomplished by a non-professional since the only steps required are the formation of a pilot hole in the air duct and the application of sealant around the misting nozzle once it is inserted through the pilot hole and in the desired position of use. The present invention can also be safely operated and maintained by a non-professional since routine maintenance is often as simple as the exchange of an empty non-pressurized fluid reservoir for a full one, and occasional adjustments to the programmable timer that may be needed when the present invention is used for a new application. The misting nozzles would preferably be made from stainless steel wrapped in brass so that they would never clog and never wear out, to assist in keeping operator maintenance to a minimum. Also, all of the electrical components within the sanitizing system control unit housing operate on 24-volt power, reducing the risk of shock hazard to any operator needing to open the housing cover and work within the interior of the housing. Safety features of the present invention also include fluid carrying tubing that has a pressure rating approximately three times that used during routine operation to prevent tubing failure in places inconvenient for access by non-professional maintenance personnel, a pump that safely operates wet or dry to guard against pump failure due to operator error in anticipating the need for reservoir refill or exchange, and the pump having a fluid recycle loop to prevent pump failure and/or operator injury in the event that the pump discharge opening should become blocked or otherwise inoperative. Further, the amount of operator maintenance is also reduced by the fully automated programmable timer of the present invention having a power loss backup, so that reprogramming of the timer is not required every time the electricity fails for a short period of time. Also, ease of manufacture and operator convenience are enhanced when the electrical components in the system control unit housing of the present invention are attached to a mounting board secured within the housing by a minimum number of fasteners. Optional use of a planar polyvinyl chloride (PVC) mounting board for electrical components that is removable from the housing not only facilitates manufacture by making it easier for the person assembling the present invention to attach the wiring between electrical components, it also facilitates servicing and replacement of electrical components since the mounting board is easily releasable from the installed housing. Since the present invention uses a plurality of nozzles that produce a mist with droplets having a maximum diameter dimension of approximately 250xcexc, and also has a fan relay that by-passes the air conditioning or heating system thermostat for prompt activation of the fan in the air conditioning or heating system associated with the present invention when the fan is not already in an operational mode so that the fan can be used for more thorough and even dispersal of the mist within the main plenum and attached air ducts, the present invention would be expected to have consistent, reliable, user-friendly, and efficient operation.
The description herein provides the preferred embodiments of the present invention but should not be construed as limiting the scope of the present air duct sanitizing invention. For example, variations may occur in the overall size of the system control unit housing as long as it remains large enough to contain all of the needed electrical components while also being sufficiently compact for easy installation and efficient use; the size of the optional mounting board for electrical components as long as it can be easily and releasably secured against the back interior wall of the housing; the size and configuration of the fluid reservoir as long as it retains an upper ridge necessary for its support within the keyhole opening through the bottom of the system control unit housing and contains an ample supply of sanitizing fluid to prevent excessive reservoir exchange; the type of material used to construct the housing and its cover as long as they remain lightweight and easily portable; the type of fastening means used between the housing and the cover; the size and type of material used for the fluid pick-up hose which connects the pump to the fluid reservoir; the number of misting nozzles connected to the pump by fluid carrying tubing; the number of misting nozzles connected to each air duct; the configuration and relative positions of the electrical components to one another within the interior of the system control unit housing; the mounting means used for fixing the electrical components securely in their usable positions within the system control unit housing; and the complement of programming features offered by the programmable timer; in addition to other obvious variations not shown or specifically described herein that are also considered without specific reference to be a part of the present invention. Thus, the scope of the present invention should be determined by the appended claims and their legal equivalents, and not limited to the examples given.